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166 Cards in this Set
- Front
- Back
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B.P.
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"before present"; present=1950
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ka, ma, bya
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thousands of years ago, millions of years ago, billions of years ago
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How long ago did the Big Bag occur?
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13.7 bya
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How long ago did the Sun form?
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~4.7 bya
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How long ago did the Earth form?
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~4.5 bya
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How long ago did the Life first occur?
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~3.5 bya
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How long ago did the first Primates, hominins, and Homo sapiens appear?
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~50-60 million ya, 5-7 million years ago, 200,000 years ago
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Subdivisions of geological time
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Eons (divided into) Eras (divided into) Periods
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Hadean Eon
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- 4600-3800 ma
- before the oldest fossil evidence of life |
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Archaean Eon
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- 3800-2500 ma
- first single-celled organisms |
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Proterozeric Eon
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- 2500-542 ma
- first simple multi-celled organisms |
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Phanerozoic Eon
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- 542ma-present
- origin and evolution of complex life forms |
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Eons of the Precambrian (oldest-->youngest)
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Hadean, Archaean, Proterozeric
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Eon of the Cambrian
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Phanerozoic
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Eras of the Phanerozoic (oldest-->youngest)
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Paleozoic, Mesozoic, Cenozoic
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Precambrian supereon
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span of time in Earth's history before the current Phanerozoic Eon; accounts for 88% of geological time
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Ediacara fauna
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multi-celled, soft-bodied marine fossil organisms
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Paleozoic era
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- 542-251 ma
- first vertebrates appeared - mostly marine at first - first land animals appear |
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Mesozoic era
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- 251-65 ma
- dinosaurs dominate, mammals and birds appear - extinction of dinosaurs at end of mesozoic |
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Cenozoic era
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- 65.5 ma
- primate and human evolution |
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fossil
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preserved remains or traces of animals, plants and other organisms from the remote past
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fossil record
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all discovered and undiscovered fossils, and also their placement in fossiliferous rock formations and sedimentary layers
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Archeological record
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body of physical evidence about cultural behaviors in the historic and prehistoric past (e.g. tools, shelters, food remains, etc)
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paleoanthropology
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study of primate and human evolution; includes fossils, genetics and behavior of living humans and nonhumans; multi-disciplinary approach
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How to make a fossil
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1) Death: rare cases of preserved remains
2) Burying/entombment prior to complete decomposition 3) Preservation: mineralization replaces bone chemicals w/rock-like minerals (also freezing, mummification, tree resin, anaerobic environments) Intervening step) deformation: fossil may be distorted and must be reconstructed 4) Discovery |
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Taphonomy
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study of what happens to plants and animals after they die
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Relative dating
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comparative method of dating the older of two or more fossils/sites, rather than providing a specific date
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Chronometric dating
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method of estimating the specific date of fossils
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Relative dating methods
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stratigraphy, fluorine dating, biostratigraphy
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Stratigraphy
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method based on fact that older remains found deeper b/c cumulative build up on earth's surface
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Flourine dating
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method based on accumulation of fluorine in a bone (more fluorine=older); comparison can tell if two bones from same site are same age
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biostratigraphy
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method that assigns age of sites based on similarity of animal remains associated with particular time periods
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Chronometric Dating Methods
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Carbon-14 dating, Argon dating, dendrochonology, fission-track dating, thermoluminescence, electron spin resonance, paleomagnetic reversal
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Carbon-14 dating
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method based on half-life of C-14 that can be applied to organic remains; useful for <50,000 years ago
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Limitations of C-14 dating
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-carbon may be replaced during fossilization
-C-14 atmosphere levels have not been constant -only useful <50,000 |
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Potassium-argon dating
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enables geologists to determine the absolute age of volcanic rocks; potassium isotopes in volcanic rock decay to argon gas; samples > 100,000 years old
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Dendrochronology
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method based on the fact that trees in dry climate accumulate one growth ring per year; samples <10,000 years old
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fission-track dating
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when uranium decays into lead in obsidian (volcanic glass), it leaves small tracks that allow to determine age (several thousand - billions ya)
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thermoluminescence
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dating method based on accumulation of electrons in heated objects
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electron spin resonances
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dating method estimating based on radioactive atoms trapped in fossils
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paleomagnetic reversal
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dating method based on shift of earth's magnetic field
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paleospecies
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species identified from the fossil record based on similarities and differences to other species
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"Lumpers"
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scientists preferring to lump new fossils into preexisting categories; believe that range of variation w/in species is large; anagenesis
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anagensis
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view that evolutionary change taking place w/in lineages
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"Splitters"
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scientists preferring to split new fossils into new species; view fossil record as evidence of frequent speciation
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variation w/in species
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-sexual dimorphism
-age differences |
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Paleocology
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study of ancient environments; e.g. study fossil pollen, plants, temp through O2 isotopes
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Stable isotope analysis
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analysis of the ratio of stable isotopes of elements that provide info about diet (e.g. ratio of C-13 to C-12 can indicate different plants eaten)
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Continental drift
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movement of continental land masses on top of a molten layer of the earth's mantle
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Continental drift during the Mesozoic/Cenozoic Era
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Pangea (225 ma) --> North vs. South continents --> continents recognizable, NA and Europe separating by Cenozoic (65 ma)
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Plesiadapiformes
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-early primate-like mammals
-paleocene epoch (65.5-55.8 ma) -NA and Europe -insectivores adapting to trees -quadrupedal, adapted for climbing |
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Non-primate features of plesiadapiformes
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-no post-orbital bar
-claws not nails -large diastema |
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diastema
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gap next to canine tooth that allows space for canine of the opposing jaw
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Carpolestes simpsoni
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-intermediate btwn primate-like and true primates
-small, arboreal fruit eater -nails and grasping foot -lacked stereoscopic vision |
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Hypotheses for explanation of primate evolution
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-nocturnal visual predation hypothesis
-angiosperm coevolution hypothesis -grasping-leaping hypothesis -narrow niche hypothesis |
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Nocturnal visual predation hypothesis
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early primates required both binocular vision and grasping hands/feet to approach insects at night
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Angiosperm coevolution hypothesis
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rise of angiosperms (flowering/fruiting plants) led to vast development and broadening of potential food sources
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Grasping-leaping hypothesis
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primate morphotype can be explained most parsimoniously by having a habitually leaping ancestor (vs. slow, cautious locomotion)
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Narrow-niche hypothesis
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primate morphological suite evolved from not only selection pressure for fine branch use, but also from a lack of engagement in other activities
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First True Primates
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-adapid and omomyids
-Eocene epoch (55.8-33.9 ma) -post-orbital bar and stereoscopic vision -grasping hands -reduced snout -teeth closer together |
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Adapids
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-first true primates
-primarily diurnal -leaf and fruit eaters - ~modern lemurs and lorises |
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Omomyids
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-first true primates
-insect and fruit eaters - ~modern tarsiers |
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Anthropoids
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- 23-35 mya
-small, arboreal primates -generalized quadrupeds -fruit, plus insects and leaves -reduction snout, vision over smell -fully enclosed eye socket -diurnal -definite example: aegyptopithecus, 33ma (North Africa) |
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Debated Anthropoids
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-Eosimias sinensis: ("Dawn Monkey of China"), 45-50 ma, combo of primitive and derived traits
-Ida (Darwinius masillae): 47 ma, actually closer to lemurs, lorises |
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Saadanius hijazensis
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-anthropoid
-29-28 ma -saudi arabia -closely related to common ancestor of Old World Monkeys and apes |
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New World Anthropoids
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-favored hypothesis is Anthropoids "rafted" from Africa to South America
-Branisella=earliest known fossil in new world (27 ma) -late Oligocene |
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Miocene Hominoids
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-miocene epoch (23-5.3 ma)
-more apes than monkeys during miocene (reversed in present) |
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Early Hominoid traits
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-brachiator anatomy changes (shoulder, arm)
-lack tail -larger avg. body size -larger brain:body -Y-5 low, rounded molars |
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Proconsul species
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-miocene ape
-21-14 ma, Africa -transition from early anthropoid to modern ape -intermembral index ~ monkey (vs. ape) -no tail -arboreal quadruped -skull/teeth ~ ape -fruit feeder |
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Sivanpithecus
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-miocene ape
-14-7 ma, Asia -skull/teeth very similar to modern orangutans -arm bones different from orangutan |
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Eugène Dubois
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-1858-1940
-believed intermediate between apes and humans -believed origins of humans in the tropics |
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Java Man
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-discovered by Dubois in 1891
-Homo erectus -first specimens of early hominid remains found outside of Africa or Europe |
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Davidson Black
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-1884-1934
-studied comparative anatomy and then human origins -discovered Peking Man (now Homo erectus) |
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Franz Weidenreich
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-1873-1948
-succeeded Davidson Black -casted Peking Man fossils (which were later lost) -exposed Piltdown hoax |
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Piltdown Hoax
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-fossil discovered in England believed to be link between ape and man
-Weidenreich exposed as a modern human cranium and orangutan jaw w/teeth filed down |
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Raymond Dart
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-1893-1988
-Australian eventually professor in S. Africa -helped ID Taung Child (1924) |
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Taung Child
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-South Africa, 1924
-Australopithecus africanus -Dart considered intermediate between apes and humans -ape-like skull and human-like teeth |
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Robert Broom
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-1866-1951
-scottish doctor -found first robust Australopithecine skull |
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"Mrs. Ples"
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-Sts 5
-South Africa, 1947 -fossil skull -once though adult woman, now adolescent male |
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Louis Leakey
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-1903-1972
-Grew up near Nairobi, Kenya -East African excavations |
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Mary Leakey
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-1913-1996
-married Louis in 1936 -discovered most complete Proconsul (miocene ape) in 1948 |
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Australopithecus boisei
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-"nutcracker man"; hominid
-1959 -Mary and Louis Leaky -robust skull w/large teeth, near stone tools |
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"Handy Man"
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-Homo habilis
-1964 -found w/tool remains -similar to Austraolipithecines -primitive face, teeth smaller but still >humans, larger brain |
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Laetoli Footprints
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-leaky discoverd in 70s
-tanzania -3.6 mya -indication of bipedalism |
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Richard Leakey
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-1944-present
-excavation near Lake Turkana in Kenya -Homo habilis and erectus skull |
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"Turkana Boy"
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-1984
-Kimoya Kimeu (working w/Rich Leakey) -near complete skeleton of Homo erectus |
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Don Johanson
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-1943-present
-American -discovered Lucy |
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Lucy
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-ethiopia, 1974
-3.2 mya -adult female -40% of skeleton -bipedal -australopithecus afarensis |
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Time White
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-1950-present
-1992 discovered almost complete female Ardipithecus ramidus ("Ardi") in Ethiopia |
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Possible reasons for origin of bipedalism (6)
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-hands free to carry tools
-hands free to carry other items (food, infants) -predator avoidance by seeing farther -foraging bipedally -increased ability to tolerate heat loss -more efficient to travel long distances |
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Hominin Features (8)
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-bipedal
-small canines -big brain -stone tools -hunting -fire -language/art/culture -living in all ecozones |
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Environment of origin of bipedalism
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probably forest/woodland
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Origins of bipedalism: carrying?
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-stone tools possible but didn't appear until ~3.4 mya
-other items: chimps walk bipedally more often when carrying valuable, unpredictable resources to less competitive areas |
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Origins of bipedalism: predator avoidance
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-many animals stand to see over savanna grasses
-but early bipeds probably in forest/woodland habitat |
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Origins of bipedalism: Foraging bipedally
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-chimps stand bipedal to collect fruits
-this standing doesn't require major anatomical alterations |
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Origins of bipedalism: Thermoregulation
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-less SA exposed to solar radiation
-higher temps lower to ground -increased convective cooling -but bipeds not on savanna, so perhaps not applicable |
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Origins of bipedalism: Efficiency of walking
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-costs less energy to cover same distance
-conserve energy when foraging |
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Possible Implications of bipedalism
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-allowed for hunting/scavenging (requires long daily travel)
-results in hairlessness (increased cooling) -running and walking both possible |
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Earliest Hominins
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-Africa, 4-7 mya
-gives ideas about first appearance of bipedalism -Sahelanthropus -Orrorin -Ardipithecus |
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Sahelanthropus tchadensis
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-Chad, Africa (2001)
-7-6 mya -bipedal, small brain, small canine, huge brow ridge -fruit diet -low male competition -foramen magnum position |
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Foramen magnum
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-large opening at base of cranium through which medulla oblongata enters and exits skull
-can indicate bipedal vs. quadruped (90deg. vs. 45 deg.) |
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Orrorin tugenensis
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-Kenya, Africa (2000)
-6.1-5.8 mya -bipedal w/ability to climb -"millenium man" -femoral head w/groove for bipedal muscle attachment -strongest evidence for oldest date of bipedalism |
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Biomechanics of the Femur
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shape and thickness of femoral head can indicate animal's locomotion
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Ardipithecus kadabba
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-Ethiopia, Africa (1997)
-5.8-5.2 mya -bipedal?, ape-like canines |
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Ardipithecus ramidus (general)
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-Ethiopia, Africa (1992-94)
-5.8-4.4 mya -bipedal, small brain (than chimps even), small canines |
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Ardipithecus unique traits
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-diet: omnivore
-no sex dimorph -dental between chimps and humans -habitat: woodland w/forest patches -not a knuckle walker, able to climb -feet: worked for both walking and climbing, divergent big toe -potential increase in male parental investment |
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Gracile Australopithecines
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-Africa, 3-4 mya
-bipedal, ability to climb -large teeth -large face -small brains -A. anamensis -A. afarensis -A. africanus -A. garhi |
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Australopithecus anamensis
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-Ethiopia, Kenya (1994)
-4.2-3.9 mya -bipedal, large canines |
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Australopithecus anamensis: teeth, lifestyle, evolution
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-ape-like teeth, parallel rows unlike parabola of humans
-bipedal w/climbing -fruits and nuts -some sex dimorph -possibly descendent of Ardipithecus -direct ancestor of australopithecus afaranesis |
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Australopithecus afarensis
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-Ethiopia, Kenya, Chad, Tanzania (1974)
-3.7-3 mya -bipedal, also arboreal? -dimorphic -larger brain then anamensis -intermediate canine -big molars -"Lucy" |
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Australopithecus afarensis: skull, teeth, locomotion, dimorph, lifestyle
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-skull ~ small ape
-transitional dental -bipedal -sex dimorph similar to humans, pair-bonding -beginning stone tool use -plant-based diet, some seeds/nuts |
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Kenyanthropus platyops
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-Kenya (2001)
-3.5-3.2 mya -small brain -jutting lower face -small molars -debates over classification |
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Australopithecus africanus
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-S.Africa (1924)
-3.3-2.5 mya -bipedal, slightly larger brain than afarensis -small canines -big molars -Taung Child, Mrs. Ples |
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Australopithecus africanus: lifestyle, evolution
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-bipedal, also climbing
-plant-based diet, some nuts/seeds -descendent of A. afarensis -possible ancestor of Homo, but maybe too specialized or wrong place |
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Australopithecus garhi
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-Ethiopia (1990)
-2.5 mya -brain ~ africanus -large molars, but different from A. afarensis -meat eating w/stone tools? -possible ancestor to homo (right place, right time) |
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Australopithecus sediba
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-possible link between Austraolopithecine and homo
-ape-like: tiny brain, long arms, chimp body size, narrow birth canal -human-like: short fingers, long thumb, brain reorganizing like humans |
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Modern Geological Time
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Panerozoic Era, Cenozoic Era, Holocene Period
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Phanerozoic Eon
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-542 ma - present
-origin and evolution of complex life forms |
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Cenozoic Era
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-65 Ma - present
-age of mammals |
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Peilstocene Period
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-1.8 Ma - 10 ka
-alternating glacial and interglacial periods |
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Holocene Period
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10ka - present
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Homo heidelbergensis
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-Europe, Africa, Asia (1908)
-200 - 800 ka (Middle Pleistocene) -Brain size=1206cc -postcrania ~ modern humans -tall, powerfully built -levallois tool tradition -hunting, fire |
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Chronospecies
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label given to different points in an evolutionary lineage of a single species over time
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Anagenesis
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evolution within a lineage over time
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Cladogenesis
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speciation and separation of a species at one point in time
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Knowledge required for Stone Tool Technology
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-tool manufacture and specific flaking methods
-characteristics of stone -mental template of the final product |
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H. heidelbergensis technology
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-first hominin associated w/Levallois
-wooden spears (found among butchered horses) -indications that they might have hunted/had first access to meat (vs. scavenging) |
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Evolution of Language (+indications)
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-relative brain surface/size
-vocal anatomy--H. sapiens have low larynx that allows speech (also increased choking risk) -hyphoid bone unique to language production |
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Homo neanderthalensis
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-Europe, Middle East (1829)
-28 - 130 ka -Brain size (1450 cc) -Postcrania: cold-adapted, powerful -Stone Tools: Mousterian Tradition -Hunting -Fire -Language -Survival of elderly, impaired |
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Neanderthal skull
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-occipital bun: protruding rear region of the skull
-1450 cc -more projecting than modern humans -large brow ridges -large nasal and midfacial regions=cold adapt |
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Neandertal postcrania
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-shorter, esp. limbs
-wider pelvis -powerfully built -matches climate (cold) |
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Mousterian tradition
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prepared-core stone tool culture of the Neandertals
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Neandertal culture
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-hunting, fire
-care of the eldery, injured -harsh life, frequent injury -evidence of deliberate burial of dead |
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Homo sapiens
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-Africa, then everywhere (1758 by Linnaeus)
-200 ka - present -brain size=1350cc -modern postcrania -upper paleolithic tools, composite tools -language -art and symbolism |
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Oldest H. sapiens remains
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-Omo (Ethiopia)
-Richard Leakey -200 ka |
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Global (historical) distribution of Modern Humans
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Africa --> middle east --> Asia --> Europe/Australia --> New World
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Why did Modern Humans Evolve
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- Changes associated with cooked diet
- Need for head stabilization during endurance running - Associated with shortened pharynx - Selection for improved vocal language skills - Selection for cognitive abilities |
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Social Brain Hypothesis
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brain size (particularly size of neocortex) most closely correlates with the size of species social group
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Neocortex
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outer layer of the cerebral hemisphere involved in higher fxns (conscious thought, language, etc)
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Social learning
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-increased sociality allows for more transmission of info
-active teaching is rare in the animal kingdom, but extraordinary in humans |
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Modern Human Technology
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-upper paleolithic
-blade technology = stone tool that is twice as long as wide -diversity of tool materials (wood, bone, etc) -composite tools (e.g. Atlatl=spear thrower) -clothing (80ka-70ka) -shelter (<20ka) |
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burin
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-stone tool w/sharp edge used to cut and engrave bone
-bone tools bwtn 90ka-40ka years ago |
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Modern Human Culture
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-cave art (early symbolism): 30ka
-statues, jewelry -complex social groups -language |
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Multiregional Evolution Model
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-proposes that modern humans emergen more or less simultaneously in major regions of the Old World from local archaic humans
-emphasizes migration -common ancestor = early H. erectus in Africa 1 mya |
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"Out of Africa" Model
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-suggests that modern human anatomy first appeared in Africa and then spread across the Old World
-African replacement model vs. Assimilation model |
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African Replacement Model
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suggest that when modern humans began migrating around the world, they replaced preexisting human populations
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Assimilation Model
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suggests that the transition to modern anatomy took place in Africa, and these changes spread to other populations through gene flow
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Mitochondrial Eve
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-lived ~ 200 kya in E. Africa
-supports Out of Africa |
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Genetic Evidence for Modern Human Origins
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-Mitochondrial Eve: supports Out of Africa
-Africa has more genetic diversity=older population -genetic diversity decreases as go farther from Africa -genetic relationships ~ geographic distance (gene flow, sequential founding of populations) -genetic variation small btwn groups and large w/in groups --> supports Out of Africa |
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Isolation by distance
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predicts that the genetic distance between populations will increase as the geographic distance between them increases
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Skin Color & UV Radiation
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-evolution of skin color balances need to protect from UV destruction of folate (dark skin) and vit d synthesis (light skin)
-global skin pigment matches predictions based on UV radiation |
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Plasticity
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ability of organisms to respond physiologically or developmentally to environmental stresses
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Acclimation
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-Acclimation = short-term physiologic responses to stress
-occurs within minutes or hours |
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Acclimatization
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-Acclimatization = long-term physiologic responses to a stress
-occurs within days or months |
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Developmental Acclimatization
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-changes in an organ or body structure that occur during the physical growth of an organism
-e.g. larger chest size in high altitudes |
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Bergmann's Rule
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among mammals of similar shape, the larger mammal loses heat less rapidly than the smaller mammal
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Allen's Rule
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states that mammals in cold climate tend to have short, bulkier limbs, allowing less loss of body heat
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Cephalic Index
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-measure of cranial shape, defined as the max width of the skull divided by the max length
-colder climates=wider skulls relative to length (higher ceph index) |
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Nasal Index
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-measure of shape of nasal opening, defined as the width of the nasal opening divided by the height
-positive association btwn nasal index and avg. temp/avg. humidity |
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Cultural Adaptations to Cold Stress
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-layered clothing
-shelter |
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Cultural Adaptation to Heat stress
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-reduce heat production
-reduce heat gain from radiation/conduction -increase evaporation -provide protection from solar radiation and hot winds |
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High-altitude adaptation
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-must compensate for lower O2, more UV, less plants/animals
-physiological changes occur: respiration increases then normal, RBC increases, aerobic capacity changes during growth |
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Horticulture and Sickle Cell Allele
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-horticulture allowed malaria mosquitos to survive better
-resulted in heterozygote advantage and mild selection for sickle cell allele |
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Lactase Persistence and Lactose Intolerance
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-recessive allele that causes human to stop producing lactase after ~ age 5
-lactose intolerance is lower in populations that have history of dairy farming |
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Current biological stresses
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-pollution
-increase in populations --> food shortage and overcrowding |
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Evolutionary Assets of H. sapiens
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-ability to adapt to different environments
-innovate -communication -cooperate -cognitive abilities in learning |
